光学CT图像引导的眼内肿瘤自适应放疗研究

External beam radiation therapy (EBRT) is considered the most common treatment modality for intraocular tumors. EBRT can not only improve the tumor control rate for intraocular tumors, but also protect the vision function of normal eyes. However, due to the relative small volume of eye balls and its involuntary movement, delivering precise radiotherapy with conformal dose distribution for intraocular tumor is difficult. Even small involuntary ocular movements may cause dose delivery errors and result in unacceptable underdosage to the tumor volume and excessive irradiation of structures at risk and surrounding healthy tissue. Image guided radiotherapy (IGRT) has been applied widely to localize the tumor position before and during treatment. However, the spatial resolution of current imaging methods used for IGRT is not sensitive enough for the small dimension of eye ball and its motion. In this situation, new imaging system with fine spatial resolution and high image quality is urgently needed to deliver precise radiation therapy for intraocular cancers. Optical coherence tomography (OCT) has become a widespread image modality in various fields of medicine particularly in ophthalmology, where its high resolution and noninvasiveness has allowed multiple applications for crosssectional and volumetric investigations of the retina and anterior segment. The current project aims to develop an eye tracking technique based on our custom-built full eye OCT system specifically for intraocular cancer and to investigate the feasibility of an OCT-based IGRT system for intraocular cancer. The specific aims of the project are as follows: 1) The current full-eye OCT system will be improved through modifying the hardware system design and combining the imaging scanner with thermoplastic masks used in radiotherapy immobilization, which will be proposed to improve the image quality and be suitable for intraocular tumor radiotherapy. 2) Multiple image registration algorithms will be developed to obtain accurate three dimensional tumor localization and real-time tracking for intraocular tumors. 3) We will develop the gate method for the radiation treatment based on real time estimation of intraocular lesions position and explore the dosimetric improvement. 4)The dosimetric discrepancy caused by the eye motion and dose compensation strategy for adaptive radiotherapy were investigated, as well as the side effect dose-volume model for normal eyes and tissues. This OCT-based IGRT technique is of great clinical benefits for intraocular cancer patients.

放射治疗已被证实可提高眼内肿瘤的局控率，保护视功能。但眼球体积微小和眼球不自主运动等特殊因素影响了眼内肿瘤的放疗精度。故临床上迫切需要发展高分辨成像技术来实现眼内肿瘤准确追踪并建立图像引导的自适应放疗以更好保护眼球正常组织。本项目将基于前期自主研发的光学CT（OCT）成像实验平台,开展基于OCT图像引导的眼内肿瘤自适应放疗研究。在前期工作基础上，改进和优化OCT成像系统，研究其扫描探头与眼内肿瘤放疗固视装置的有效整合方式；基于OCT图像与计划CT图像研究眼内肿瘤三维定位和实时跟踪的图像配准技术，并在此基础上寻找眼内肿瘤和器官的运动规律；基于OCT图像获取的肿瘤运动信号，引导眼内肿瘤放疗，建立门控放疗方法，通过与常规计划相比，探索新技术在剂量学上的获益；评估基于图像引导的靶区和危及器官的实际剂量分布规律，尝试构建个体化的剂量优化补偿模型，对未来临床实现眼内肿瘤的精确放疗及减少并发症奠定基础。

本项目针对眼部肿瘤精准放射治疗过程中眼球精细且有不自主运动的难点，创造性地在放疗过程中引进光学相干断层扫描（OCT）技术，通过对OCT设备的改造，OCT与CT图像融合配准研究，利用OCT技术精准确定眼部肿瘤位置并进行实时跟踪，提高眼部肿瘤的放射治疗剂量分布，尝试构建个体化的剂量模型。.项目的执行过程中，通过改进和提升现有SD-OCT系统，设计全新的眼部放疗辅助装置，并与放疗系统整合，建立眼内肿瘤位置的实时定位和追踪系统；提出了一种OCT 与CT图像自动多模态图像配准策略，实施基于OCT眼前节组织特征信息（如虹膜、晶状体等）的图像分割和配准算法，通过配准参数实时确定眼内肿瘤位置，实现放疗过程中非损伤、更为精确定位和实时追踪眼内肿瘤的目的；通过引进OCT的图像引导放射治疗技术，提高了眼部肿瘤放疗剂量分布，减少周围正常组织的放疗剂量和并发症。.项目相关结果成果在Phys Med Biol，Eur Radiol，Precision Radiation Oncology，J Appl Clin Med Phys等国际医学物理主流的杂志上发表论文10多篇，并以口头报告形式在国际医学物理协会年会和其它本领域国际，国内会议上报告。相关的OCT眼部肿瘤精准定位和实时跟踪技术获国家发明专利2项。项目负责人获得了浙江省高校领军人才培养计划;浙江省卫健委医坛新秀培养对象;浙江省151人才培养人员;温州市科技创新领军人才等称号。顺利晋升正高级工程师，获硕士生导师，留学生博导资格，当选亚太医学物理联盟教育培训委员会主席，美国应用临床医学物理杂志副主编，中国医师协会放射肿瘤治疗分会肿瘤放疗人工智能与大数据学组委员，中国生物医学工程学会医学物理分会青委会副主委，浙江省医学会放射肿瘤治疗学分会副主委，浙江省抗癌协会放射物理专委会副主委等。培养了2名硕士，获医院研究生心中的最美导师称号。